Energy is the material basis for human society to survive, and is also an important resource for social and economic development. Since the industrial revolution, kerosene, gas oil and fossil fuels gradually become the main energies for production and life. However, excessive consumption of fossil fuels in today's society highlights the growing problem of energy crisis and environmental protection. Hence, the developments of green energies as ideal alternative energies are in full swing. The green energy, such as solar power, requires a maximum power point tracker and an electrical charging/discharging circuit to form a DC power supply. Yet, the traditional mechanism for regulating the output voltage of the DC power supply only processes a single signal of output voltage yet ignores the control and protection of inductor current, which may easily result in burning the power component owing to over-flowing current.
Therefore, methods were developed for current control. For example, Brad Bryant proposed peak current mode control (PCMC) in 2005 (Brad Bryant and Marian K. Kazimierczuk, “Modeling the Closed-Current Loop of PWM Boost DC-DC Converters Operating in CCM With Peak Current-Mode Control, “IEEE Trans. on Circuits and Systems, Vol. 52, No. 11, November 2005.); and, Yingyi Yan et al. proposed average current-mode control (ACMC) in 2014 (Yingyi Yan, Fred C. Lee, Paolo Mattavelli and Pei-Hsin Liu, “I2 Average Current Mode Control for Switching Converters, “IEEE Trans. on Power Electronics, Vol. 29, No. 4, April 2014.). They control and protect the switching element through current inner-circuit, but these control methods still have some drawbacks.
In a paper, Lloyd Dixon described shortcomings of PCMC that a distortion might happen owing to the error value between the peak value and the average value and that its ability on preventing noise interference was not good (Lloyd H. Dixon, “Average Current Mode Control of Switching power Supplies,” Unitrode Application, Vol. 3, pp. 356-359, 1999.). The control method of PCMC is to switch the state to off after the peak inductor current reaches the command of reference current, which is not done by comparing the current average to the command of reference current. Therefore, when the inductor current ripple is big, duty ratio may be decreased due to the error value between the peak value and the average value and the regulation mechanism of output voltage may be further affected.
In another paper, Tsai-Fu Wu et al. described a shortcoming of ACMC about the slow response to output voltage (Tsai-Fu Wu, Chih-Hao Chang, Li-Chiun Lin, and Yung-Ruei Chang, “Current Improvement for a 3φ Bi-directional Inverter with Wide Inductance Variation,” 8th International Conference on Power Electronics—ECCE Asia, May 30-Jun. 3, 2011.). ACMC has an extra set of filters in the current inner-circuit to filter out instant inductance current for solving the problem of the distortion made by PCMC owing to the error value between the peak value and the average value and filtering out the current ripple happened on switching the power element. Consequently, as compared to PCMC, ACMC has a better ability of preventing noise interference. However, an extra set of filter is required with the difficulty of design increases and relatively reduces the speed of responding the output voltage.
Hence, the prior arts do not fulfill all users' requests on actual use.